Mark, a relatively conventional college student in San Francisco was just watching a parade when he noticed a stunning blonde gal watching and smiling at him. It wasn't long before the gal (Misty) and her husband (Andy) approached Mark and struck up a conversation. That led to drinks together as the sexy lady touched Mark's arm and thigh. She made it clear she found him attractive.
A few days later Mark got a call from Andy, inviting him to have dinner with him and his wife. Getting into Andy's car, Mark soon learned that dinner was to be at the couple's luxurious high-rise condo. Andy told him he would be leaving Mark with his wife as he ran an errand "so you and Misty can enjoy some appetizerseach other!"
Inside the condo it did not take Mark long to understand the meaning of Andy's words. During Andy's absence Misty was all over Mark, eventually orally feasting at Mark's crotch as her "appetizer". That led to the two of them being in bed together when Andy returned. Quickly both guys were teaming up to give Misty elevated levels of feminine pleasure.
After that first round Andy explained that he has been looking for a handsome young man to be an extra lover for Misty to keep her pleasured during his frequent business trips. It did not take Mark long to agree to be her extra lover. Eventually they asked him to move in with them, using their extra bedroom, even allowing Mark to use his new digs to entertain his girlfriends then they were not there.
The unique three-way friendship lasted four years. During that time Mark regularly filled his role as Misty's extra lover and often joined Andy in doubling her pleasure. One day when one of Mark's girlfriends was visiting and they were in the throes of passion, Misty walked in and decided to join them. That was her first experience with girl-girl pleasures.
At Andy's urging, Mark even set up a couple multiple-guy experiences for Misty. Since Andy was sterile, one of those "events" was set up during a fertile time while Misty was off birth control. The objective was successful. Nine months later Misty had a baby boy. As the organizer of the "event", Mark now considers himself the boy's uncle.